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node of Ranvier

...low-capacitance electrical insulator. However, nodes of Ranvier interrupt the insulation at intervals, and this discontinuity enables impulses to jump from node to node in a process known as
saltatory conduction.

role in nervous system

...of ion channels, which, upon stimulation, propagate the nerve impulse to the next node. In this manner the action potential jumps quickly from node to node along the fibre in a process called
saltatory conduction (from Latin
saltare, “to jump”).